Polyimides (PI) are heterocyclic polymers commonly prepared by the condensation reaction of an aromatic diamine with an aromatic dianhydride or derivative thereof and having a repeat unit of the general structure ##STR1## where Ar is a tetravalent aromatic radical such as 1,2,4,5-tetrasubstituted benzene. Ar may also be a bis(o-diphenylene) having the general structure ##STR2## where Y=nil, O, S, SO.sub.2, CO, C(CH.sub.3).sub.2, or any other appropriate divalent radical. Ar' is a divalent aromatic radical which may be 1,3-phenylene, 1,4-phenylene, 4,4'-biphenylene, 4,4'-oxydiphenylene, 4,4'-sulfonyldiphenylene, or any other appropriate divalent radical.
The synthesis and characterization of PI has been extensively studied and documented. Reviews on PI are available. [J. W. Verbicky, Jr., "Polyimides" in Encyclopedia of Polymer Science and Engineering, 2.sup.nd Ed., John Wiley and Sons, New York, Vol. 12, 364 (1988); C. E. Sroog, Prog. Polym. Sci., 16, 591 (1991)].
A variety of monomers, oligomers and polymers containing ethynyl (acetylenic) and substituted ethynyl (i.e. phenylethynyl) groups have been reported. The ethynyl groups in the polymer is either pendent to the chain, in the chain, or at the chain ends. Many of these materials have been used to prepare coatings, moldings, adhesives and composites [P. M. Hergenrother, "Acetylene Terminated Prepolymers" in Encyclopedia of Polymer Science and Engineering, John Wiley and Sons, New York, Vol. 1, 61 (1985)]. Good processability by either solution casting and/or compression molding have been observed for the ethynyl and substituted ethynyl containing materials. In general, thermally cured ethynyl and substituted ethynyl containing materials exhibit a favorable combination of physical and mechanical properties. Some ethynyl endcapped materials such as the Thermid.RTM. resins are commercially available (National Starch and Chemical Co., Bridgewater, N.J. 08807). Phenylethynyl containing amines have been used to terminate imide oligomers [F. W. Harris, A. Pamidimuhkala, R. Gupta, S. Das, T. Wu, and G. Mock, Poly. Prep., 24 (2), 325, 1983; F. W. Harris, A. Pamidimuhkala, R. Gupta, S. Das, T. Wu, and G. Mock, J. Macromol. Sci.-Chem., A21 (8 & 9), 1117 (1984); C. W. Paul, R. A. Schultz, and S. P. Fenelli, "High-Temperature Curing Endcaps For Polyimide Oligomers" in Advances in Polyimide Science and Technology, (Ed. C. Feger, M. M. Khoyasteh, and M. S. Htoo), Technomic Publishing Co., Inc., Lancaster, Pa., 1993, p. 220; R. G. Byrant, B. J. Jensen, and P.M. Hergenrother, Poly. Prepr., 34 (1), 566, 1993]. Imide oligomers terminated with ethynyl phthalic anhydride [P. M. Hergenrother, Poly. Prep., 21 (1), 81, 1980], substituted ethynyl phthalic acid derivatives [S. Hino, S. Sato, K. Kora, and O. Suzuki, Jpn. Kokai Tokkyo Koho JP 63, 196, 564. Aug. 15, 1988; Chem. Abstr., 115573w, 110, ( 1989)] and phenylethynyl containing phthalic anhydrides have been reported. Imide oligomers containing pendent substituted ethynyl groups [F. W. Harris, S. M. Padaki, and S. Varaprath, Poly. Prepr., 21 (1), 3, 1980 (abstract only), B. J. Jensen, P. M. Hergenrother, and G. Nwokogu, Polymer, 34 (3), 630, 1993; B. J. Jensen and P. M. Hergenrother, U.S. Pat. No. 5,344,982 (Sep. 6, 1994)] have been reported.
This present invention constitutes new composition of matter. It concerns novel diamines containing phenylethynyl groups and new imide oligomers and co-oliogmers containing pendent phenylethynyl groups. The polymers and copolymers prepared from these materials exhibit a unique and unexpected combination of properties that includes higher glass transition temperatures after curing and higher retention of neat resin, adhesive and carbon fiber reinforced mechanical properties at temperatures up to 204.degree. C. under wet conditions without sacrificing melt flow behavior and processability as compared to similar materials.
Another object of the present invention is to provide materials that are useful as adhesives, coatings, films, moldings and composite matrices.
Another object of the present invention is the composition of several new diamines containing pendent phenylethynyl groups.